Sawdust burner



mvgmoR ANDREWA DEN BY ATTORNEY Jan. 12, 1932.

A. A. HALDEN SAWDUST BURNER Filed Dec. 24, 1928 Patented Jan. 12, 1932 'ATEN-T oFFicE sawnnsr BURNER Application filed December 24, 1928. Serial No. 328,077.

This invention relates to sawdust burners and it refers particularly to burners of the gravity feed type and to an improved means associated with the burner grates; for the elimination of explosions that are resultant to clogging or choking of the hopper and then a sudden dropping of alarge mass of saw dust into the fire box. I

Explanatory to the invention, it will be here stated that in sawdust burners of this type, as are now quite extensively used, explosions are quite frequent because ofclogging-ofthe sawdust in the hopper,-w1th a subsequent dropping of the material after that in the fire box-has burned out. This dropping of themass of sawdust into the fire box or ignition chamber .naturally'closes off all of the air draft-and circulation, thus 7 causing an explosion. Such explosions are '20 not onlyannoying but are also. dangerous andmany residence fires have resulted from this cause. V

In view ofthe above, it has been the principal object of this invention to provide means 2 whereby complete clogging of the fire box by the fuel is not possible, and-whereby an air passageis alwayslmaintained through the fire box for the flow of air to the combustion chamber so that explosions are prevented and a more complete combustion of fuel than heretofore is insured.

More specifically, the invention resides in the provision of an air draft bridge of a novel construction that is adapted to be mounted on the grate bars of the burner so as to maintain an open air passage through the fire box and into the combustion chamber; this bridge being disposed lengthwise of the 4 fire box and transversely of the grates, and is so constructed as to form a dividing ridge with outwardly and downwardly inclined, opposite side walls provided with lateral openings for the distribution of air to opposite sides of the fire box and also for the admittance of a certain amountof sawdust into the air draft passage provided by the bridge.

Other objects of the invention reside in the various details of construction and in the an opening 2 adjacent the base thereof into combination of parts, as willhereinafter be described. a r I j In accomplishing these and other objects of the invention, I have provided the improved details of construction, the preferred forms of which are illustrated in the accompanying drawings, wherein- Figure" l'is a vertical cross section taken lengthwise of a burner firebox, showing the Y arrangement of the air draft bridge upon .60 the grate bars.

Fi-gure2 is a vertical cross section taken on the line 2-2 in Figure 1, illustrating the ridge-like character of the air draft bridge.

Figure 8 is a perspective view of the air draft bridge as'mounted on the grate bars.

Referring more in detail to the drawings 1 designates what may be a furnace of any of the ordinary types of construction, having which the end portion of the sawdust burner fire box is extended. The burner, in its en-. tirety, is designated by reference numeral 3 and this may be-one of any of the ordinary types as are now generally in'use. As here I shown, the burner comprises the metallic fire box portion 4, which s of rectangular, cross section, as indicated in Figure 2, and is provided at the outer end with an opening 5 over which a door6 is hingedly suspended. The door is provided with the usual damper 7 that is adjustable for regulating 'theafiow of'air into the fire box. In the top wall of the fire box, toward the forward end thereof, is an opening 8 through which the lower end of-a feed hopper 9 is extended for the delivery of fuel by gravity flow into the fire-box and onto the grate bars. In Figure l, the fuel, which may be sawdust or the like, is indicated-at 10 and as it flows from the hopper it is directed onto the-grates by means of an upwardly inclined plate 11. i V In the device illustrated, there are aplurality of grate bars 12 arranged in downwardly stepped relation from the outer end of the fire box-to the inner end; the grates being spaced so as to leave airpassages 13 between each of the adjacent bars. "The grate bars aresup-. ported at their opposite ends by the opposite side frames 15 which aredisposed closelyxadjacent the side walls of the fire box and the fire box is lined, as is the usual practice, with a suitable fire brick 16 to prevent overheating of the metallic outer walls and also for the purpose of confining the heat within the burner.

The gist of the present invention resides in the provision of the air draft bridge bar 17 which is disposed upon the grate bars, as is shown best in Figure 3, so as to extend from the lower end of the plate 11 and above the adjacent grate bar toward the inner end of the fire box; the bridge bar terminating just within the passage which leads into the furnace. This bridge bar is disposed centrally of and lengthwise of the fire box and trans versely with respect to the grates. It is of metal construction, cast or otherwise formed, and is in the form of a pointed ridge whereby the flow of sawdust from the hopper is divided and directed toward opposite sides of the fire box. In cross section, the bridge is of inverted, V-shape and which provides an air passage 20 lengthwise within it for the flow of air from the forward end of the box, as admitted through the air draft damper in the door, to the combustion chamber. In the sloping, opposite side walls of the bridge are openings 21 for the admittance of a certain amount of sawdust into the air passage or for the delivery of air to the opposite sides of the fire box.

WVhile I have illustrated the air draft bridge as being associated with a burner embodying stepped grate bars, it is not intended that it be confined in its use only to this arrangement, but that it may be designed for use in burners using stepped grates, flat grates or grates of other arrangement.

Assuming the parts to be so constructed and arranged, it is readily apparent that should the hopper mouth become clogged and the sawdust within the fire box burns away, a subsequent dropping of the mass of sawdust from the hopper into the fire box will not cause the latter to become clogged for the reason that the bridge bar at all times maintains an air draft passage which will positively prevent the occurrence of explosions that otherwise would occur. The present bar also acts after the fashion of a hot air blast, since it provides for a flow of air into the combustion chamber, thereby insuring a more complete combustion of the fuel than heretofore has been possible. The device also provides for easier and quicker starting of a fire and also for an easier maintenance of a fire after it has been started.

The arrangement of the bridge with the side openings provides for feeding of the fuel in certain amounts into the air passage and toward the center thereof. This fuel is easily and quickly ignited and is carried into the combustion chamber where complete combustion takes place.

It is readily apparent that various details of construction could be altered to adapt the device to various types of burners without departing from the spirit of the invention and, for this reason, it is not desired that my claims be limited only to the device as it is here shown.

Having thus described my invention, what I claim as new therein and desire to secure by Letters-Patent, is:

1. In a burner of the character described, comprising a fire box opening into a combustion chamber, a hopper for gravity feed of fuel into the fire box and a grate within the fire box, an air draft bridge disposed upon the grate lengthwise of the fire box; said bridge comprising inclined, opposite sidewalls forming a dividing ridge whereby fuel from the hopper is diverted to opposite sides of the fire box, and providing within the bridge an unrestricted air passage opening directly into the combustion chamber and supplied by air from beneath the grates.

2. In a sawdust burner ofthe character described, comprising a fire box and a combustion chamber, a series of grates within the fire box stepped downwardly toward the combustion chamber and providing passages for the inlet of air between them, and an air draft bridge disposed centrally of and lengthwise of the fire box and transversely of the grates and forming a horizontal dividing ridge for diverting fuel delivered thereonto to opposite sides of the fire box; said bridge forming an unrestricted air passage for the feeding of fresh air to the combustion chamber and comprising inclined, opposite side walls having openings therein for the admittance of air into the fire box.

Signed at Seattle, Washington, this 11th day of December 1928.

AiIDnEW A. HALDEN. 

